Liquid formulation and a method for making electronic devices by solution process

ABSTRACT

Liquid formulation comprising a solute for fabricating an electronic device and a partially or fully deuterated solvent is disclosed. The liquid formulation can be used in the solution process of electronic devices, and can greatly enhance the device performance of solution processed OLEDs, especially lifetime. Also disclosed is a method of making an electronic device.

This application is a continuation of U.S. Utility patent applicationSer. No. 16/134,997, filed Sep. 19, 2018 and claims the benefit of U.S.Provisional Application No. 62/566,293, filed Sep. 29, 2017, the entirecontent of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a solvent for organic electronicdevices, such as organic light emitting devices. More specifically, thepresent invention relates to a deuterated liquid formulation forsolution process and a method of manufacturing electronic devices.

BACKGROUND ART

An organic electronic device is preferably selected from the groupconsisting of organic light-emitting diodes (OLEDs), organicfield-effect transistors (O-FETs), organic light-emitting transistors(OLETs), organic photovoltaic devices (OPVs), dye-sensitized solar cells(DSSCs), organic optical detectors, organic photoreceptors, organicfield-quench devices (OFQDs), light-emitting electrochemical cells(LECs), organic laser diodes and organic plasmon emitting devices.

In 1987, Tang and Van Slyke of Eastman Kodak reported a bilayer organicelectroluminescent device, which comprises an arylamine holetransporting layer and a tris-8-hydroxyquinolato-aluminum layer as theelectron and emitting layer (Applied Physics Letters, 1987, 51 (12):913-915). Once a bias is applied to the device, green light was emittedfrom the device. This invention laid the foundation for the developmentof modern organic light-emitting diodes (OLEDs). State-of-the-art OLEDsmay comprise multiple layers such as charge injection and transportinglayers, charge and exciton blocking layers, and one or multiple emissivelayers between the cathode and anode. Since OLED is a self-emittingsolid state device, it offers tremendous potential for display andlighting applications. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on flexible substrates.

OLED can be categorized as three different types according to itsemitting mechanism. The OLED invented by Tang and van Slyke is afluorescent OLED. It only utilizes singlet emission. The tripletsgenerated in the device are wasted through nonradiative decay channels.Therefore, the internal quantum efficiency (IQE) of a fluorescent OLEDis only 25%. This limitation hindered the commercialization of OLED. In1997, Forrest and Thompson reported phosphorescent OLED, which usestriplet emission from heave metal containing complexes as the emitter.As a result, both singlet and triplets can be harvested, achieving 100%IQE. The discovery and development of phosphorescent OLED contributeddirectly to the commercialization of active-matrix OLED (AMOLED) due toits high efficiency. Recently, Adachi achieved high efficiency throughthermally activated delayed fluorescence (TADF) of organic compounds.These emitters have small singlet-triplet gap that makes the transitionfrom triplet back to singlet possible. In the TADF device, the tripletexcitons can go through reverse intersystem crossing to generate singletexcitons, resulting in high IQE.

OLEDs can also be classified as small molecule and polymer OLEDsaccording to the forms of the materials used. Small molecule refers toany organic or organometallic material that is not a polymer. Themolecular weight of a small molecule can be large as long as it has welldefined structure. Dendrimers with well-defined structures areconsidered as small molecules. Polymer OLEDs include conjugated polymersand non-conjugated polymers with pendant emitting groups. Small moleculeOLED can become a polymer OLED if post polymerization occurred duringthe fabrication process.

The emitting color of an OLED can be achieved by emitter structuraldesign. An OLED may comprise one emitting layer or a plurality ofemitting layers to achieve desired spectrum. In the case of green,yellow, and red OLEDs, phosphorescent emitters have successfully reachedcommercialization. Blue phosphorescent emitters still suffer fromnon-saturated blue color, short device lifetime, and high operatingvoltage. Commercial full-color OLED displays normally adopt a hybridstrategy, using fluorescent blue and phosphorescent yellow, or red andgreen. At present, efficiency roll-off of phosphorescent OLEDs at highbrightness remains a problem. In addition, it is desirable to have moresaturated emitting color, higher efficiency, and longer device lifetime.

There are various methods for OLED fabrication. Small molecule OLEDs aregenerally fabricated by vacuum thermal evaporation. Polymer OLEDs arefabricated by solution process. If the material can be dissolved ordispersed in a solvent, the small molecule OLED can also be produced bysolution process. Thus it can be seen that the OLEDs can be manufacturedby vacuum thermal evaporation (VTE) and solution process. The solutionprocess includes spin-coating, inkjet printing, slit printing, and otherprinting methods. Solution process has long been considered as thealternative to VTE due to its potential advantage on large areafabrication and cost reduction. However, the device performance ofsolution processed OLEDs, especially lifetime, has been falling behindVTE OLEDs. It is critical to improve the lifetime of solution processedOLEDs to realize their commercial potential.

For solution process, the first step is to dissolve or suspend thematerials in solvents. The solution or suspension is then used forcoating or printing. Therefore, it is believed that solvents play animportant role in the device performance. They can often affect themorphology of the film, resulting in different transporting and opticalproperties. Sometimes the solvent residue is hard to get rid ofespecially for those high boiling solvents used in inkjet printing. Wehave found that the device lifetime of solution processed OLEDs can begreatly enhanced by introducing deuterated solvents, which has not beenreported in literature.

SUMMARY OF THE INVENTION

The present invention aims to provide a solution to improve theperformance of solution processed OLEDs. The device performance ofsolution processed OLEDs, especially lifetime, can be greatly enhancedby introducing deuterated solvents.

According to an embodiment of the present invention, a liquidformulation is disclosed, which comprising a solvent and a solute forfabricating an electronic device, wherein the solvent is partially orfully deuterated.

According to another embodiment, a method of making an electronic deviceis disclosed, which comprising forming a liquid composition, wherein thesolvent is partially or fully deuterated.

The liquid formulation and manufacture method disclosed in the presentinvention can be used in the solution process of electronic devices. Thedevice performance of solution processed OLEDs, especially lifetime, canbe greatly enhanced by introducing partially or fully deuteratedsolvents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an organic light emitting device that can bemade by the method using of the liquid formulation disclosed herein.

FIG. 2 schematically shows another organic light emitting device thatcan be made by the method using of the liquid formulation disclosedherein.

DETAILED DESCRIPTION

OLEDs can be fabricated on various types of substrates such as glass,plastic, and metal foil. FIG. 1 schematically shows the organic lightemitting device 100 without limitation. The figures are not necessarilydrawn to scale. Some of the layer in the figure can also be omitted asneeded. Device 100 may include a substrate 101, an anode 110, a holeinjection layer 120, a hole transport layer 130, an electron blockinglayer 140, an emissive layer 150, a hole blocking layer 160, an electrontransport layer 170, an electron injection layer 180 and a cathode 190.Device 100 may be fabricated by depositing the layers described inorder. The properties and functions of these various layers, as well asexample materials, are described in more detail in U.S. Pat. No.7,279,704 at cols. 6-10, which are incorporated by reference in itsentirety.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of host materials are disclosed inU.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated byreference in its entirety. An example of an n-doped electron transportlayer is BPhen doped with Li at a molar ratio of 1:1, as disclosed inU.S. Patent Application Publication No. 2003/0230980, which isincorporated by reference in its entirety. U.S. Pat. Nos. 5,703,436 and5,707,745, which are incorporated by reference in their entireties,disclose examples of cathodes including compound cathodes having a thinlayer of metal such as Mg:Ag with an overlying transparent,electrically-conductive, sputter-deposited ITO layer. The theory and useof blocking layers is described in more detail in U.S. Pat. No.6,097,147 and U.S. Patent Application Publication No. 2003/0230980,which are incorporated by reference in their entireties. Examples ofinjection layers are provided in U.S. Patent Application Publication No.2004/0174116, which is incorporated by reference in its entirety. Adescription of protective layers may be found in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety.

The layered structure described above is provided by way of non-limitingexample. Functional OLEDs may be achieved by combining the variouslayers described in different ways, or layers may be omitted entirely.It may also include other layers not specifically described. Within eachlayer, a single material or a mixture of multiple materials can be usedto achieve optimum performance. Any functional layer may include severalsublayers. For example, the emissive layer may have a two layers ofdifferent emitting materials to achieve desired emission spectrum.

In one embodiment, an OLED may be described as having an “organic layer”disposed between a cathode and an anode. This organic layer may comprisea single layer or multiple layers.

An OLED can be encapsulated by a barrier layer to protect it fromharmful species from the environment such as moisture and oxygen. FIG. 2schematically shows the organic light emitting device 200 withoutlimitation. FIG. 2 differs from FIG. 1 in that the organic lightemitting device 200 include a barrier layer 102, which is above thecathode 190. Any material that can provide the barrier function can beused as the barrier layer such as glass and organic-inorganic hybridlayers. The barrier layer should be placed directly or indirectlyoutside of the OLED device. Multilayer thin film encapsulation wasdescribed in U.S. Pat. No. 7,968,146, which is herein incorporated byreference in its entirety.

Devices fabricated in accordance with embodiments of the invention canbe incorporated into a wide variety of consumer products that have oneor more of the electronic component modules (or units) incorporatedtherein. Some examples of such consumer products include flat paneldisplays, monitors, medical monitors, televisions, billboards, lightsfor interior or exterior illumination and/or signaling, heads-updisplays, fully or partially transparent displays, flexible displays,smart phones, tablets, phablets, wearable devices, smart watches, laptopcomputers, digital cameras, camcorders, viewfinders, micro-displays, 3-Ddisplays, vehicles displays, and vehicle tail lights.

The materials and structures described herein may be used in otherorganic electronic devices listed above.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processable” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

It is believed that the internal quantum efficiency (IQE) of fluorescentOLEDs can exceed the 25% spin statistics limit through delayedfluorescence. As used herein, there are two types of delayedfluorescence, i.e. P-type delayed fluorescence and E-type delayedfluorescence. P-type delayed fluorescence is generated fromtriplet-triplet annihilation (TTA).

On the other hand, E-type delayed fluorescence does not rely on thecollision of two triplets, but rather on the transition between thetriplet states and the singlet excited states. Compounds that arecapable of generating E-type delayed fluorescence are required to havevery small singlet-triplet gaps to convert between energy states.Thermal energy can activate the transition from the triplet state backto the singlet state. This type of delayed fluorescence is also known asthermally activated delayed fluorescence (TADF). A distinctive featureof TADF is that the delayed component increases as temperature rises. Ifthe reverse intersystem crossing rate is fast enough to minimize thenon-radiative decay from the triplet state, the fraction of backpopulated singlet excited states can potentially reach 75%. The totalsinglet fraction can be 100%, far exceeding 25% of the spin statisticslimit for electrically generated excitons.

E-type delayed fluorescence characteristics can be found in an exciplexsystem or in a single compound. Without being bound by theory, it isbelieved that E-type delayed fluorescence requires the luminescentmaterial to have a small singlet-triplet energy gap (ΔE_(S-T)). Organic,non-metal containing, donor-acceptor luminescent materials may be ableto achieve this. The emission in these materials is often characterizedas a donor-acceptor charge-transfer (CT) type emission. The spatialseparation of the HOMO and LUMO in these donor-acceptor type compoundsoften results in small ΔE_(S-T). These states may involve CT states.Often, donor-acceptor luminescent materials are constructed byconnecting an electron donor moiety such as amino- orcarbazole-derivatives and an electron acceptor moiety such asN-containing six-membered aromatic rings.

Definition of Terms of Substituents

halogen or halide—as used herein includes fluorine, chlorine, bromine,and iodine.

Alkyl—contemplates both straight and branched chain alkyl groups.Examples of the alkyl group include methyl group, ethyl group, propylgroup, isopropyl group, n-butyl group, s-butyl group, isobutyl group,t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octylgroup, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group,n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecylgroup, n-heptadecyl group, n-octadecyl group, neopentyl group,1-methylpentyl group, 2-methylpentyl group, 1-pentylhexyl group,1-butylpentyl group, 1-heptyloctyl group, 3-methylpentyl group.Additionally, the alkyl group may be optionally substituted. The carbonsin the alkyl chain can be replaced by other hetero atoms. Of the above,preferred are methyl group, ethyl group, propyl group, isopropyl group,n-butyl group, s-butyl group, isobutyl group, t-butyl group, n-pentylgroup, and neopentyl group.

Cycloalkyl—as used herein contemplates cyclic alkyl groups. Preferredcycloalkyl groups are those containing 4 to 10 ring carbon atoms andincludes cyclobutyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl,4,4-dimethylcylcohexyl, 1-adamantyl, 2-adamantyl, 1-norbornyl,2-norbornyl and the like. Additionally, the cycloalkyl group may beoptionally substituted. The carbons in the ring can be replaced by otherhetero atoms.

Alkenyl—as used herein contemplates both straight and branched chainalkene groups. Preferred alkenyl groups are those containing two tofifteen carbon atoms. Examples of the alkenyl group include vinyl group,allyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group,1,3-butandienyl group, 1-methylvinyl group, styryl group,2,2-diphenylvinyl group, 1,2-diphenylvinyl group, 1-methylallyl group,1,1-dimethylallyl group, 2-methylallyl group, 1-phenylallyl group,2-phenylallyl group, 3-phenylallyl group, 3,3-diphenylallyl group,1,2-dimethylallyl group, 1-phenyl1-butenyl group, and 3-phenyl-1-butenylgroup. Additionally, the alkenyl group may be optionally substituted.

Alkynyl—as used herein contemplates both straight and branched chainalkyne groups. Preferred alkynyl groups are those containing two tofifteen carbon atoms. Additionally, the alkynyl group may be optionallysubstituted.

Aryl or aromatic group—as used herein contemplates noncondensed andcondensed systems. Preferred aryl groups are those containing six tosixty carbon atoms, preferably six to twenty carbon atoms, morepreferably six to twelve carbon atoms. Examples of the aryl groupinclude phenyl, biphenyl, terphenyl, triphenylene, tetraphenylene,naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene,chrysene, perylene, and azulene, preferably phenyl, biphenyl, terphenyl,triphenylene, fluorene, and naphthalene. Additionally, the aryl groupmay be optionally substituted. Examples of the non-condensed aryl groupinclude phenyl group, biphenyl-2-yl group, biphenyl-3-yl group,biphenyl-4-yl group, p-terphenyl-4-yl group, p-terphenyl-3-yl group,p-terphenyl-2-yl group, m-terphenyl-4-yl group, m-terphenyl-3-yl group,m-terphenyl-2-yl group, o-tolyl group, m-tolyl group, p-tolyl group,p-t-butylphenyl group, p-(2-phenylpropyl)phenyl group,4′-methylbiphenylyl group, 4″-t-butyl p-terphenyl-4-yl group, o-cumenylgroup, m-cumenyl group, p-cumenyl group, 2,3-xylyl group, 3,4-xylylgroup, 2,5-xylyl group, mesityl group, and m-quarterphenyl group.

Heterocyclic group or heterocycle—as used herein contemplates aromaticand non-aromatic cyclic groups. Hetero-aromatic also means heteroaryl.Preferred non-aromatic heterocyclic groups are those containing 3 to 7ring atoms which includes at least one hetero atom such as nitrogen,oxygen, and sulfur. The heterocyclic group can also be an aromaticheterocyclic group having at least one heteroatom selected from nitrogenatom, oxygen atom, sulfur atom, and selenium atom.

Heteroaryl—as used herein contemplates noncondensed and condensedhetero-aromatic groups that may include from one to five heteroatoms.Preferred heteroaryl groups are those containing three to thirty carbonatoms, preferably three to twenty carbon atoms, more preferably three totwelve carbon atoms. Suitable heteroaryl groups includedibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene,benzofuran, benzothiophene, benzoselenophene, carbazole,indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole,triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole,thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine,oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole,indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline,isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine,phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine,phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine,thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine,preferably dibenzothiophene, dibenzofuran, dibenzoselenophene,carbazole, indolocarbazole, imidazole, pyridine, triazine,benzimidazole, 1,2-azaborine, 1,3-azaborine, 1,4-azaborine, borazine,and aza-analogs thereof. Additionally, the heteroaryl group may beoptionally substituted.

Alkoxy—it is represented by —O-Alkyl. Examples and preferred examplesthereof are the same as those described above. Examples of the alkoxygroup having 1 to 20 carbon atoms, preferably 1 to 6 carbon atomsinclude methoxy group, ethoxy group, propoxy group, butoxy group,pentyloxy group, and hexyloxy group. The alkoxy group having 3 or morecarbon atoms may be linear, cyclic or branched.

Aryloxy—it is represented by —O-Aryl or —O-heteroaryl. Examples andpreferred examples thereof are the same as those described above.Examples of the aryloxy group having 6 to 40 carbon atoms includephenoxy group and biphenyloxy group.

Arylalkyl—as used herein contemplates an alkyl group that has an arylsubstituent. Additionally, the arylalkyl group may be optionallysubstituted. Examples of the arylalkyl group include benzyl group,1-phenylethyl group, 2-phenylethyl group, 1-phenylisopropyl group,2-phenylisopropyl group, phenyl-t-butyl group, alpha.-naphthylmethylgroup, 1-alpha.-naphthylethyl group, 2-alpha-naphthylethyl group,1-alpha-naphthylisopropyl group, 2-alpha-naphthylisopropyl group,beta-naphthylmethyl group, 1-beta-naphthylethyl group,2-beta-naphthylethyl group, 1-beta-naphthylisopropyl group,2-beta-naphthylisopropyl group, p-methylbenzyl group, m-methylbenzylgroup, o-methylbenzyl group, p-chlorobenzyl group, m-chlorobenzyl group,o-chlorobenzyl group, p-bromobenzyl group, m-bromobenzyl group,o-bromobenzyl group, p-iodobenzyl group, m-iodobenzyl group,o-iodobenzyl group, p-hydroxybenzyl group, m-hydroxybenzyl group,o-hydroxybenzyl group, p-aminobenzyl group, m-aminobenzyl group,o-aminobenzyl group, p-nitrobenzyl group, m-nitrobenzyl group,o-nitrobenzyl group, p-cyanobenzyl group, m-cyanobenzyl group,o-cyanobenzyl group, 1-hydroxy-2-phenylisopropyl group, and1-chloro2-phenylisopropyl group. Of the above, preferred are benzylgroup, p-cyanobenzyl group, m-cyanobenzyl group, o-cyanobenzyl group,1-phenylethyl group, 2-phenylethyl group, 1-phenylisopropyl group, and2-phenylisopropyl group.

The term “aza” in azadibenzofuran, aza-dibenzothiophene, etc. means thatone or more of the C—H groups in the respective aromatic fragment arereplaced by a nitrogen atom. For example, azatriphenylene encompassesdibenzo[f,h]quinoxaline, dibenzo[f,h]quinoline and other analogues withtwo or more nitrogens in the ring system. One of ordinary skill in theart can readily envision other nitrogen analogs of the aza-derivativesdescribed above, and all such analogs are intended to be encompassed bythe terms as set forth herein.

The alkyl, cycloalkyl, alkenyl, alkynyl, aralkyl, heterocyclic group,aryl, and heteroaryl may be unsubstituted or may be substituted with oneor more substituents selected from the group consisting of deuterium,halogen, alkyl, cycloalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclicamino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, an acyl group, a carbonyl group, a carboxylic acid group, anether group, an ester group, a nitrile group, an isonitrile group, asulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group,and combinations thereof.

It is to be understood that when a molecular fragment is described asbeing a substituent or otherwise attached to another moiety, its namemay be written as if it were a fragment (e.g. phenyl, phenylene,naphthyl, dibenzofuryl) or as if it were the whole molecule (e.g.benzene, naphthalene, dibenzofuran). As used herein, these differentways of designating a substituent or attached fragment are considered tobe equivalent.

In the compounds mentioned in this disclosure, multiple substitutionsrefer to a range that includes a double substitution, up to the maximumavailable substitutions.

According to an embodiment of the present invention, a liquidformulation comprising a solvent and a solute for fabricating anelectronic device is disclosed, wherein the solvent is partially orfully deuterated.

In one embodiment, wherein the electronic device is an OLED.

In one embodiment, wherein the electronic device is photovoltaic device.

In one embodiment, wherein the electronic device is a transistor.

In one embodiment, wherein the solute comprises a hole injectionmaterial.

In one embodiment, wherein the solute comprises a hole transportingmaterial.

In one embodiment, wherein the solute comprises a host and an emitter.

In one embodiment, wherein the solute comprises an electron transportingmaterial.

In one embodiment, wherein the solvent has a boiling point between 70°C. to 300° C. at 1 atmosphere.

In one embodiment, wherein the solvent comprises a halogen group, asubstituted or unsubstituted alkyl group having 1 to 20 carbon atoms, asubstituted or unsubstituted cycloalkyl group having 3 to 20 ring carbonatoms, a substituted or unsubstituted heteroalkyl group having 1 to 20carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to20 carbon atoms, a substituted or unsubstituted aryloxy group having 6to 30 carbon atoms, a substituted or unsubstituted alkenyl group having2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6to 30 carbon atoms, a substituted or unsubstituted heteroaryl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted alkylsilylgroup having 3 to 20 carbon atoms, a substituted or unsubstitutedarylsilyl group having 6 to 20 carbon atoms, a substituted orunsubstituted amino group having 0 to 20 carbon atoms, an acyl group, acarbonyl group, a carboxylic acid group, an ester group, a nitrilegroup, an isonitrile group, a sulfanyl group, a sulfinyl group, asulfonyl group, or a phosphino group.

In one preferred embodiment, wherein the solvent is selected from thegroup consisting of:

In one embodiment, wherein the electronic device is fabricated byprinting.

According to another embodiment, a method of making an electronic deviceis disclosed. The method of making an electronic device comprisesforming a liquid composition comprising a solvent and a solute forfabricating an electronic device is disclosed, wherein the solvent ispartially or fully deuterated.

Combination with Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. The combinations ofthese materials are described in more detail in U.S. Pat. App. No.20160359122 at paragraphs 0132-0161, which are incorporated by referencein its entirety. The materials described or referred to the disclosureare non-limiting examples of materials that may be useful in combinationwith the compounds disclosed herein, and one of skill in the art canreadily consult the literature to identify other materials that may beuseful in combination.

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a varietyof other materials present in the device. For example, emissive dopantsdisclosed herein may be used in combination with a wide variety ofhosts, transport layers, blocking layers, injection layers, electrodesand other layers that may be present. The combination of these materialsis described in detail in paragraphs 0080-0101 of U.S. Pat. App. No.20150349273, which are incorporated by reference in its entirety. Thematerials described or referred to the disclosure are non-limitingexamples of materials that may be useful in combination with thecompounds disclosed herein, and one of skill in the art can readilyconsult the literature to identify other materials that may be useful incombination.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. The present invention as claimed may therefore includevariations from the particular examples and preferred embodimentsdescribed herein, as will be apparent to one of skill in the art. Manyof the materials and structures described herein may be substituted withother materials and structures without deviating from the spirit of theinvention. It is understood that various theories as to why theinvention works are not intended to be limiting.

1. A liquid formulation comprising a liquid organic solvent and a solute for fabricating an electronic device, wherein the organic solvent is partially or fully deuterated, and wherein the solute is dissolved or dispersed in the liquid organic solvent and comprises a hole injection material, or a hole transporting material, or a host and an emitter.
 2. The liquid formulation of claim 1, wherein the electronic device is an OLED.
 3. The liquid formulation of claim 1, wherein the electronic device is photovoltaic devices.
 4. The liquid formulation of claim 1, wherein the electronic device is a transistor.
 5. The liquid formulation of claim 1, wherein the liquid organic solvent has a boiling point between 70° C. to 300° C. at 1 atmosphere.
 6. The liquid formulation of claim 1, wherein the liquid organic solvent comprises a halogen group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms, a substituted or unsubstituted alkylsilyl group having 3 to 20 carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to 20 carbon atoms, a substituted or unsubstituted amino group having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, a nitrile group, an isonitrile group, a sulfanyl group, a sulfinyl group, a sulfonyl group, or a phosphino group.
 7. The liquid formulation of claim 1, wherein the liquid organic solvent is selected from the group consisting of:


8. The liquid formulation of claim 1, wherein the electronic device is fabricated by printing.
 9. A method of enhancing lifetime of OLEDs by fabricating the OLEDs with a liquid formulation comprising a liquid organic solvent and a solute, wherein the liquid organic solvent is partially or fully deuterated, and wherein the solute is dissolved or dispersed in the liquid organic solvent and comprises a hole injection material, or a hole transporting material, or a host and an emitter. 